There is an air-conditioning apparatus that allows a heat source side refrigerant circulated through a refrigeration cycle (refrigerant circuit) to exchange heat with an indoor side refrigerant (heat medium) circulated through a heat medium circuit. The refrigeration cycle includes an outdoor unit and a relay unit connected by pipes. The heat medium circuit includes the relay unit and an indoor unit connected by pipes. Air-conditioning apparatuses having such a configuration used as building multi-air-conditioning apparatuses include an air-conditioning apparatus configured such that conveyance power for the heat medium is reduced to achieve energy saving (refer to Patent Literature 1, for example). The reason why the two circuits are arranged as described above is that a refrigerant, such as water, having no adverse effects on health of users in a building can be used as the heat medium circulated in an indoor space.